package Lab5;
/**
 * 实验 5 
 * 问题 3. 对给定的表格信息进行信息挖掘。
 */
import java.io.IOException;
import java.util.*;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;

public class Lab5P03 {
    public static int time = 0;
    /**
     * @param args
     * 输入一个child-parent的表格
     * 输出一个体现grandchild-grandparent关系的表格
     */
    //Map将输入文件按照空格分割成child和parent，然后正序输出一次作为右表，反序输出一次作为左表，需要注意的是在输出的value中必须加上左右表区别标志
    public static class Map extends Mapper<Object, Text, Text, Text>{
        public void map(Object key, Text value, Context context) throws IOException,InterruptedException{
            String child_name = new String();
            String parent_name = new String();
            String relation_type = new String(); //左右表区分标志：1表示左表，2表示右表
            String line = value.toString();
            int i = 0;
            while(line.charAt(i) != ' ') {
                i++;
            }
            String[] values = {line.substring(0,i),line.substring(i+1)};
            if(values[0].compareTo("child") != 0) {
                child_name = values[0];
                parent_name = values[1];
                relation_type = "1";
                context.write(new Text(values[1]), new Text(relation_type+"+"+child_name+"+"+parent_name)); //左表
                relation_type = "2";
                context.write(new Text(values[0]), new Text(relation_type+"+"+child_name+"+"+parent_name)); //右表
            }
        }
    }
    
    public static class Reduce extends Reducer<Text, Text, Text, Text>{
        public void reduce(Text key, Iterable<Text> values,Context context) throws IOException,InterruptedException{
            if(time == 0){   //输出表头
                context.write(new Text("grand_child"), new Text("grand_parent"));
                time++;
            }
            int grand_child_num = 0;
            String grand_child[] = new String[10];
            int grand_parent_num = 0;
            String grand_parent[]= new String[10];
            Iterator ite = values.iterator();
            while(ite.hasNext()){
                String record = ite.next().toString();
                int len = record.length();
                int i = 2;
                if(len == 0) continue;
                char relation_type = record.charAt(0);
                String child_name = new String();
                String parent_name = new String();
                //获取value-list中value的child
    
                while(record.charAt(i) != '+'){
                    child_name = child_name + record.charAt(i);
                    i++;
                }
                i=i+1;
                //获取value-list中value的parent
                while(i<len){
                    parent_name = parent_name+record.charAt(i);
                    i++;
                }
                //左表，取出child放入grand_child
                if(relation_type == '1'){
                    grand_child[grand_child_num] = child_name;
                    grand_child_num++;
                }
                else{//右表，取出parent放入grand_parent
                    grand_parent[grand_parent_num] = parent_name;
                    grand_parent_num++;
                }
            }
    
            if(grand_parent_num != 0 && grand_child_num != 0 ){
                for(int m = 0;m<grand_child_num;m++){
                    for(int n=0;n<grand_parent_num;n++){
                        context.write(new Text(grand_child[m]), new Text(grand_parent[n]));
                        //输出结果
                    }
                }
            }
        }
    }
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        Configuration conf = new Configuration();
        conf.set("fs.default.name","hdfs://localhost:9000");
        String[] otherArgs = new String[]{"input","output"}; /* 直接设置输入参数 */
        if (otherArgs.length != 2) {
            System.err.println("Usage: wordcount <in><out>");
            System.exit(2);
            }
        Job job = Job.getInstance(conf,"Single table join");
        job.setJarByClass(Lab5P03.class);
        job.setMapperClass(Map.class);
        job.setReducerClass(Reduce.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);
        FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
        FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}
